1. Field of the Invention
Geothermal Well Head Assembly.
2. Description of the Prior Art
The drilling of geothermal wells to produce pressurized fluid for power generating purposes has developed only recently on a large scale in the United States. Such drilling and production has in the main been carried out by companies previously engaged in the production of petroleum.
Consequently, there has been a tendancy to employ the same well head equipment that was satisfactory for the production of oil to geothermal wells, but with unsatisfactory results. Operational difficulties encountered in adapting oil field well head equipment to geothermal wells involve the expansion and contraction of the string of production casing in the geothermal wells due to variations in temperature, and the failure of conventional oil well head assemblies to withstand for prolonged period of time the abrasive action of high velocity pressurized fluid having particles of solid material entrained therewith.
The replacement or repair of conventional oil well head assemblies that have been utilized on geothermal wells and been damaged for the reasons above stated, have in the past required that the geothermal wells be shut down by pumping mud into the bores thereof. This procedure is undesirable for a geothermal well that has been so shut down may be ruined, or the future production of pressurized fluid therefrom seriously impaired.
A major object of the present invention is to provide a well head assembly for use on geothermal wells that allows the string of production casing to expand and contract longitudinally in a bore hole without placing a substantial strain on the well head assembly, and one in which the seals between the production casing and well head assembly may be periodically adjusted from the ground surface without shutting down the well.
Another object of the invention is to furnish a geothermal well head assembly that may be operated either manually or by pressurized fluid, and one in which interior components that have been damaged by the abrasive action of the pressurized geothermal fluid may be removed for replacement or repair, without shutting down the geothermal well.
These and other objects and advantages of the invention will become apparent from the following description of a preferred form of the invention and certain alternate forms thereof.